In recent years, a liquid crystal display device, which is an example of display devices, has become more advanced in function, and levels of properties that are expected of the liquid crystal display device are increasingly becoming high. The properties which the liquid crystal display device is expected to possess are, for example, high luminance, high resolution, reduced thickness and weight, lower power consumption, and the like.
For example, Patent Literature 1 discloses a technology in which (i) in order to increase an aperture ratio of a liquid crystal display device, a pixel electrode is arranged to overlap with various wires and (ii) a film having a high transmittance is used as an interlayer insulating film so as to enable effective use of light from a backlight. Specifically, the liquid crystal display device includes: switching elements, gate wires, and source wires; an interlayer insulating film provided over the switching elements, the gate wires, and the source wires; pixel electrodes which are provided on the interlayer insulating film; and an electrode which connects each of the pixel electrodes and a drain to each other over a gate wire or an additional capacitance wire through a contact hole which penetrates through the interlayer insulating film.
Meanwhile, Patent Literature 2 discloses a technology for providing an active matrix substrate having excellent electric characteristics. The technology allows an oxide semiconductor film to be easily used as a semiconductor channel film of a TFT (thin-film transistor) as well as reducing the number of steps of a photoengraving (production) process. Specifically, the active matrix substrate is configured such that: a plurality of pixels are arranged in matrix; each of the plurality of pixels includes a gate electrode, a common electrode, a gate insulating film, an oxide transparent film, a source electrode, a drain electrode, and a pixel electrode; the oxide transparent film has a conductor region and a semiconductor region; the conductor region is provided (i) below the source electrode and the drain electrode and (ii) in a portion which is connected to a lower part of the drain electrode and extends to above a part of the common electrode so as to constitute the pixel electrode; the semiconductor region is provided in a portion which corresponds to a lower layer of a region between the source electrode and the drain electrode so as to constitute a channel region of the thin-film transistor; and the source electrode and the drain electrode are electrically connected to the conductor region of the oxide transparent film.